In general, the color of light reflected by an object is influenced by the color of the light source. The human brain is able to detect and correct such variations in color. The human eye adapts to color changes in sunny and hazy weather and under indoor incandescent or fluorescent lighting so that the color of white-colored objects remains consistent. However, the color of white colored objects produced by digital image obtaining devices is not exactly the same in different light sources. For example, a picture captured in an environment illuminated by a tungsten filament lamp may be yellowish, while a picture captured in another environment may be bluish or reddish. In order to approximate human visual perception, a digital image obtaining device adjusts color on the basis of light rays and defines what white is so that the device can reproduce what human eyes see as white in the final image. This adjustment is referred to as white balance.
In currently available technology, the parameters for white balance correction, automatic white balance (AWB), and white balance ratio (WB ratio) all affect the adjusted colors. White balance correction makes adjustments according to the red average value and blue average value (Ravg, Bavg) of a device itself, AWB makes adjustments according to different gains associated with environmental changes, and WB ratio makes adjustments according to different color temperatures and brightness levels.
However, only one set of parameters is used when white balance adjustment is performed using currently available technology. When there exists a significant difference between the hardware of different devices, the color representation of the different devices will vary significantly in the same environment. For example, in the same scenario, images provided by one device may be reddish while images provided by another device may be bluish. Using a single set of parameters to perform white balance adjustment may result in inaccurate white balance correction, which could affect imaging results.